This invention relates to a feed meter for conveyed material, and particularly for the control of the application rate of additives to conveyed material.
In many processing systems it is necessary or desirable to measure the throughput or feed rate of material being processed or conveyed. For example, in the storage of forage or grain, chemicals are added to inhibit microbial activity. A significant deterrant to the use of chemicals for enhanced preservation of forage and grain is the inability to apply them evenly, and at the required application rate. The ratio of the applied chemical to the forage and grain is often quite small. Small application rates makes uniform distribution difficult. Portions which have insufficient chemicals are not suitably protected while portions which have too much is a waste of the chemical. Furthermore, an excess of some chemicals can be harmful to animals injesting the treated feed. It is generally impractical to disburse granular or liquid additives evenly in stored forage or grain. Therefore the only feasible method is to apply the chemical as it is processed or conveyed. For example, forage harvesters and balers can be used for field treatment of forage. Forage blowers and grain augers can be used while elevating forage and grain.
With present methods the chemical flow rate of the applicator is based on a calibration of the throughput of the forage or grain with respect to time, and this is often in error. Furthermore fluctuations in the throughput or feed rate of the processor or conveyor may or may not be compensated by the operator, and small fluctuations go unnoticed. The normal condition is over or under application of the chemical resulting in a chemical loss and uneven distribution at best. At worst over application can cause feed toxicity. Also the loss of some chemicals to the atmosphere can make it hazardous for the operator.